Battery problem

I have this Interstate battery installed 3 years ago.  Its label says
it's good for 64 months.  Now it's only been 36 months.  I jump-
started my car yesterday and drove it on local streets for about 20
minutes.  I assume that's enough to recharge it.  But today my car is
dead again.

Since I know nothing about cars.  I have some questions to ask.  1st,
please take a look at the picture that I linked, is that a maintenance-
free battery?

http://i37.tinypic.com/29osrvr.jpg

2nd. On the nagative terminal (right), there is some brownish bubble-
like stuff.  Is that corrosion?  Should I wipe the terminal clean?

3rd, I'm reading battery maintenance online right now.  They all say
check to see if the battery has low fluid level.  If it's not
maintenance-free kind, I assume the two black pieces on top of this
battery are the caps I should remove and take a peek inside.  Right?

4th, How much distilled water should I add?  Where do I get distilled
water?

That's probably too many questions asked here.  And you might suggest
just go get a new battery.  But it'll help me to learn a bit about
*cars*.  Thanks.